border-1px($col)
	position:relative
	&:after
		position:absolute
		display:block
		left:0
		bottom:0
		width:100%
		border-top:1px solid $col
		content:''
border-none()
	&:after
		display: none
borderup-1px($col)
	position:relative
	&:before
		position:absolute
		top:0
		left:0
		width:100%
		border-bottom:1px solid $col
		content:''
bg-image($url)
	background-image: url($url+ "@2x.png")
	@media (-webkit-min-device-pixel-ratio:3),(min-device-pixel-ratio:3)
		background-image: url($url+ "@3x.png")
